1. Field of the Invention
The present invention relates to systems for controlling valve response. More particularly, the invention relates to systems for controlling the response of solenoid-operated, pneumatic/hydraulic, discrete, low-cost on-off valves commonly used in machine and robotic applications.
2. Description of the Prior Art
In pneumatic/hydraulic systems requiring valves, it is often highly desirable to use simple, low cost on-off valves, so-called xe2x80x9cbang-bangxe2x80x9d valves, for controlling the transfer of media. Unfortunately, unlike more complex and expensive fully proportional valves, on-off valves actuate abruptly, which stresses mechanical parts, jars loads, and makes intricate movements difficult. Thus, though simple and economical, on-off valves are presently not well-suited for use in some systems and applications.
For example, an aerial truck, or xe2x80x9cbucket truckxe2x80x9d, has a hydraulic, valve-actuated boom with a platform or enclosure located at one end thereof for carrying a worker. The boom is operable to raise and position the worker for performing, for example, work on pole-mounted electrical transformers, telephone wires, or television cables. If the hydraulic valves controlling the boom provide jerky rather than smooth movements, the boom could be dangerously stressed, or the enclosure or worker could be jarred into contact with the electrical lines, wires, or cables, or inadvertently brought into injurious contact with nearby structures.
For these and other reasons an improved valve control system is needed whereby a proportional response can be achieved with minimal expense and complexity using low cost on-off valves.
The control system of the present invention includes novel enabling technology that overcomes the disadvantages of existing valve control systems to make the use of low-cost on-off valves practical in applications for which they were previously not well suited. A proportional response is achieved from a on-off valve by interposing a single continuously proportional inlet valve controlled by ramp-like or non-linear signals to regulate the transfer of a media, whether gas or fluid, to the one or more actuated on-off valves and to the functions associated with those valves. The signals are preferably provided by a microcontroller that can be preprogrammed to produce a variety of signal types, including ramp, ramp-like, and non-linear.
The result is a relatively simple, low-cost valve system providing a greater degree of control and smoothness of media transfer than is currently available without using numerous expensive proportional valves or complex valve actuation schemes. The preferred control system also allows for application specific customization, including linearization of non-linear mechanical responses.
These and other important aspects of the present invention are more fully described in the section entitled DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT, below.